Marcel depeez



(No Model.)

M. DEPREZ.

RHEOSTAT 0R RHBOTGME.

Patented Sept. 30. 1890.

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' Ronneb- PATENT OEEICE.

MARCEL DEPREZ, OF PARIS, FRANCE.

RH EOSTAT OR RHEOTOME.

SPECIFICATION forming part of Letters Patent No. 437,412, datedSeptember Application filed February 24, 1888. Serial No. 265,206. (Nomodel.) Patented in France October 5, 1887, No. 186,243,- in EnglandFebruary 7, 1888, No. 1,843, and in Belgium February 7,

To all when@ t may concern:

Be it known that I, MARCEL DEPREZ, electrician engineer, of Paris, inthe Republic of France, have invented certain new and usefulImprovements in Rheostats and Rheotomes, (for which I have obtainedLetters Patent in France, dated October 5, 1887, No. 186,248; in GreatBritain, dated February 7, 1888, No. 1,843, and in Belgium, datedFebruary 7, 1888, No. 80,5G2,) of which the following is aspecification.

In nearly all applications of electricity to industrial purposes it isusual to employ rheostats essentially composed of more or less resistingconductors in which a part of the electric energyis expended in heat.Vhen great electric powers are employed, developed by very intensecurrents, the rheostats expend very notable quantities of energy, and itbecomes proportionately diiiicult to construct them with the conductingbodies usually employed, especially metals. The problem is even morecomplicated if the currents employed are of high tension. Powerfulhightension currents do not bear the introduction of rheostats exceptwith special precautions, and cannot be suddenly broken by the ordinarymeans. In practice metallic rheostats are always employed. These act byintroducing the resistances into the current by successive fractions.NVith currents of high tension this process produces violent and suddenchanges of potential, which cause extra currents and dangerous sparks.On the other hand, the currents cannot be broken Without having firstreduced them to a very weak intensity, without which extra currents andsparks, which are very prejudicial to the apparatus, are engendered.This condition with high-tension currents requires the employment ofvery high resistances, which never quite fulfill their object when theyare obtained with the aid of metals.

Now, the rheostat-s which form the subject of the present inventionpermit of obtaining very easily as high a resistance as is desired, andof introducing it into the circuit by following a continuous variation,of maintaining it at a determined value with an absolute pressure, andof breaking the current without stats are applied to currents a sensiblespark. In order to obtain these result-s I employ liquids as theresisting bodies. This employment of liquid is not newin principle. Ithas been sometimes followed in laboratories and in experiments g but,for reasons hereinafter explained, liquids have never been employedindustrially, and there is no liquid rheostat in current use. Thearrangements hereinafter described have for their object to allow ofthis industrial use of liquids, and to thereby obtain all itsadvantages.

In all these arrangements there are five general characteristic andnovel features, which I will first explain.

The first consists in the nature of the liquid employed. In thelaboratory experiments above referred to more or less concentratedsaline solutions have been used; but according to this invention Iemploy ordinary water. I use saline solutions only exceptionally, incases where it is necessary to reduce the resistance-such as, forexample, when rheoof relatively weak tension or of great intensity.

The second characteristic feature is that, in order to be able to keepthe rheostat indefinitely in the current, I provide for a continuousrenewal of the liquid, so that the electrodes are immersed not in astagnant mass but in a current of liquid. The use of ordinary watermakes this method very simple, as it is simply a continuous flow. In thecase of saline solutions the same liquid can be kept circulating throughthe rheostat (and through a refrigerator, if necessary) by a pump orother analogous apparatus.

The third characteristic feature of my improved rheostat is that theelectrodes never come in contact in the liquid, so that the resistanceot' the rheostat is never actually reduced to Zero. This I consider agreat advantage, for when metallic contact is broken within a resistingiiuid, and when the circuit carries a current of considerable tension,the spark occurs between the electrodes within the iiuid, although suchspark is never as great and destructive as if the circuit is brokensuddenly outside of the resisting fluid. I have, however, provision forremoving the rheostat completely from the circuit IOO by short-circuiting the same loutside ofV the iiuid by connecting the metallicconresisting ductors which lead to the rheostat. This connection takesplace automatically and by the continuation of the action which hasreduced the resistance to its minimum value. The rheostat is thenoutside the circuit. In` versely, when it is desired to reintroduce it,the metallic contact is first disconnected, and then the resistance ofthe rheostat' is increased.

The fourth characteristic feature applies to rheostats which areemployed as rheotomes. In this case, in order to interruptthe current byone of the arrangements which are hereinafter described, provision ismade for the electrodes or one of them ceasing to be 'in contact withthe liquid. When one ofV the electrodes has to leave the liquid beforethe other, it is important for this to be the one which is connected tothe positive pole-that is to say, the one by which the current entersthe rheostat.

, The fifth characteristic feature is that the electrodes which conductthe current to the rheostat and lead it away therefrom are notnecessarily the current, such as carbon or platinum, for example, whichare expensive and fragile. I

` use, on the contrary, ordinary cheap metals,

such as iron or lead. Their waste or wear in the apparatus is very slow,and the renewal by like electrodes is inexpensive.

Having set out the general characteristic features of novelty, I willnow proceed to describe the arrangements for carrying them into effectwith reference to the accompanying drawings, in which I liaveshownseveral forms of apparatus embodying my invention.

j They are divided into three classes, viz: First,

arrangements in which the electrodes are movable; second, arrangementsin which the electrodes are fixed aud the liquid is movable, and, third,arrangements in which neither the electrodes nor liquid is movable.

Figure 1 represents a vertical section of a rheostat in which oneelectrode is movable. Fig.2 is a like view of a rheostat in which bothelectrodes are movable. Figs. 3, 4., 5, 6, 7, and 7bis are also verticalsections of rheostats in which the highresistance iiuid is movable,while the electrodes are practically stationary. Fig. 8 is a similarview of an apparatus in which an insulating partition between theelectrodes is movable within the -erably three,

'ner F to the other pole.

formed of metals or materials. which are not attacked under the actionof consists inx placing in a vessel athrough which a current of liquidflows, two, or prefelectrodes F F F', the two outer F F being connectedto one pole and the i11- It suices to raise the electrodes F in order togradually increase the resistance and to withdraw it from the liquid tobreak the current withou't producing extra current even by moving theelectrode rapidly. Both electrodes may be movable and rise from theliquid together. (See Fig. 2.) Y Instead of a narrow vessel which onlyallows of a vertical movement, I can employ a long vessel or troughwhich allows of the electrodes being moved away from each other beforewithdrawing one of them in order to break the current. The variation ofthe resistance is thus more regular. A complete apparatus `for effectingthis is described farther on. 'lhe plates forming the electrodes haveiianges at their lower ends. These flanges retain for an instant a filmof liquid when the plates are raised from the body of the liquid,whereby the resistance of the circuit is enormously increased at thatpoint bei.

fore the circuit is entirely broken, and thereby entirely prevent theformation of arcs and sparks wh en the current is broken. Thisprovisionis useful, but is not considered necessary.

In the arrangements above described, in

which the electrodes are movable in the liquid,l

when the electrodes are rising the whole body of liquid continues toconduct the current,- `the resistance being increased only by thediminution of the submerged surface of the electrodes; but when, on theother hand, the body of liquid diminishes at the same time as thesubmergedsurface of the electrodes the resistance increases with greaterregularity.

, Fig. 3 represents an arrangement in which the body of liquiddiminishes. The electrodes F and F are fixed in an insulating-vessel ct.

'The liquid enters the vessel by an orifice A and leaves by the orificeB of a vertical tube made of non-conducting material. This tube can bemoved endwise in a gland or stuiiingbox C, and the height of its upperend determines the level of liquid between the electrodes, andconsequently the resistance.

Fig. it represents-another arrangementin which, by means of a bell o rinverted vessel b of insulating material descending around an electrodeF, the liquid-level can -be lowered. For more security this bell can bedouble, so as to surround both the electrodes F F', as seen in Fig. 5.The liquid can bev moved without moving' the bell or inverted vesseleither by blowing into the bell b, in

which the electrodes are, (see Fig. 6,)*or byv forcing it by a pressureof air from aclosed reservoir a, Fig. 7, into a vessel b', in which- TOOITO

W'hen neither the electrodes nor the liquidy are made to move, thevariation of the resistance be effected by introducing aninsulating-partition CZ between the electrodes. (See Fig. 8.) This modecan be very eficiently carried out by the arrangement shown in Figs. 9and l0, in which the rheostat is in the form of a fiat cylindricalvessel capable of turning upon a horizontal axis o 0. The vessel ispartly divided by a vertical semicircular partition C, parallel to theends. The electrodes F F are likewise semicircular and are ixed. Theyare submerged in the liquid, the level of whichis at N and the renewalof which is effected by connections at the center of the vessel. Byturning the vessel the insulatingpartition can be completely disengagedfrom or more or less engaged between the electrodes or interposedentirely between them, thus causing the resistance to vary from theminimum to the maximum by a simple and rapid operation. Vith thisarrangement the vessel can inversely be fixed, the insulatingpartition Cbeing dispensed with and the electrodes being movable around the axis.They could then be more or less submerged in the liquid or be entirelywithdrawn from it. The variation of the resistance would,how ever, beless regular than with the other arrangement.

The arrangement which I will now proceed to describe, and which isrepresented in. Figs. ll and l2, is a veryl practical i'orm of apparatusof the class in which the electrodes or one of them are movable. Theliquid is contained in a vessel or trough V of insulating material. Itenters by an orifice A and leaves by an orifice B. Its level isdetermined by a partition Il, the height of which can be varied, ifnecessary. The electrodes F F are each formed ot' parallel metallicplates connected together. The electrode F is iixed and receives thecurrent from a binding-screw a. The electrode F is movable and suspendedfrom an axis o. The plates of this electrode are parallel with those ofthe other, and can enter between them, as is indicated in Fig. l2, butwithout touching them. The bottom of the vessel is curved, the curvebeing struck from the axis from which the movable electrode issuspended. The current reaches this electrode through this axis.

The rod which supports the movable electrode is connected to a lever G,and a counter-weight tends to keep the rheostat open, so as to avoidaccidents if the rheostat should by mistake be left to itself. Accordingto the position given to the lever G the movable electrode F will eitherbe near the electrode F, and the resistance will then be very small ormoved away from this electrode, the resistance being proportionatelygreater, or if the electrode F be moved quite out of the water thecurrent will be broken. On the axis of the lever is a inger C connectedby a rod D of insulating material to a handle m adjoining thelever-handle M. Vhen the movable electrode F reaches the bottom of thevessel and the lever-handle M is let go, the iinger C touches a block Eand makes a metallic contact, putting the rheostat out o'E circuitinversely It the rheostat is to be used, the two handles areV graspedtogether, and consequently the finger C is raised and the rheostat isautomatically put into the circuit.

That I claim, and desire to secure by Letters Patent, is-

l. In a rheostat or rheotome in which a liquid forms the resisting body,the combination, with the vessel for containing said liquid and with theelectrodes, of an inlet for said liquid and an outlet for the same,whereby a continuous flow and consequent renewal of the liquid ismaintained, as set Jforth.

2. In a liquid rheostat or rheotome, electrodes formed with langes attheir lower ends, whereby when said electrodes cease to be submerged inthe liquid a film is momentarily retained by said flanges, as set forth.

3. In a liquid rheostat or rheotome, the combination, with a vessel V,having an inlet A and outlet B and with the electrodes F and F', of therod I), lever G, contact-finger C, contact-block E, rod D, and handles Mand in, as described and shown, for the purpose set forth.

In testimony whereof I have signed my name to this specification in thepresence ot two subscribing witnesses.

MARCEL DEPREZ.

Vitnesses:

RoB'r. M. HooPER, ALBERT COHEN.

